DESCRIPTION: This K05 Senior Scientist Award proposal is intended to enhance the P.I.'s percent research effort in studies of the neural mechanisms of attentional processes in humans. Attentional mechanisms include the control systems for top-down (voluntary) and bottom-up (reflexive) attention, as well as the modulatory effects these control systems exert on perceptual processes. The goal of this proposal is to combine psychophysical measures, event-related potential (ERP) recording and functional magnetic resonance imaging (fiviRI) in healthy and patient populations to investigate attentional mechanisms. Three main areas of investigation are proposed: (1) Attentional control mechanisms are proposed to involve a variety of brain systems that support different computational operations, yet, little evidence links specific brain system to distinct attentional functions. This proposal will investigate attentional control processes in a variety of paradigms for feature and form-based attention in cortical and subcortical systems using ERP and event-related fMRI methods to isolate activity related to specific aspects of attentional task performance. (2) It is now well accepted that attention can influence neuronal processing in visual cortex, but little is actually known about how these effects are engaged in sensory cortex, or how processing in early visual areas are modulated by various forms of elementary (feature-based) and higher-order (form-based) attentional selection. This proposal will investigate the functional properties of feature and form-based selective attention in functionally-defined visual areas. (3) Neurological damage leads to a variety of attentional disorders. The present proposal will investigate attentional processing in patients with cortical lesions using ERPs to provide a link between neuropsychological research in patients, and psychophysical and functional imaging studies in healthy persons; this research will focus on attentional control mechanisms. A theme of this proposal is the combined use of ERPs and fMRI to provide complementary measures of attentional processes that emphasize temporal and spatial aspects of neural activity, respectively. This proposal will permit the P.I. to dedicate greater effort toward investigating attentional mechanisms, and to advance research productivity by taking full advantage of the P.I.'s new research environment at Duke University. Deficits in attentional function accompany psychiatric and neurological diseases, and thus investigations of the basic mechanisms of brain attention mechanisms will yield essential core knowledge in the effort to characterize, diagnose and treat such conditions in humans.